New research reveals that mushrooms are “without a doubt” the highest known single source of the antioxidants ergothioneine and glutathione, which are both associated with anti-aging properties.

A team of researchers from Pennsylvania State University found that mushrooms are surprisingly full of both compounds, and that some of the 13 species they tested contained vastly higher levels than others. Common white button mushrooms, for instance, had low levels of the two antioxidants compared to some other mushrooms but still higher levels than your average non-mushroom food. The winner “by far” was the wild porcini mushroom, which is convenient since it’s also delicious. And even though some foods lose their health benefits when you cook them, the antioxidants in the mushrooms appear heat-stable and thus unaffected. The research was recently published in the journal Food Chemistry.

"There's a theory—the free radical theory of aging—that's been around for a long time that says when we oxidize our food to produce energy there's a number of free radicals that are produced that are side products of that action and many of these are quite toxic," said Robert Beelman, professor emeritus of food science and director of the Penn State Center for Plant and Mushroom Products for Health, in a Penn State news release. "The body has mechanisms to control most of them, including ergothioneine and glutathione, but eventually enough accrue to cause damage, which has been associated with many of the diseases of aging, like cancer, coronary heart disease and Alzheimer's."

Robert Beelman is professor emeritus of food science at Penn State and director of the Center for Plant and Mushroom Foods for Health. Pennsylvania State University/Patrick Mansell

Antioxidants have been elevated to near-mythical status through the wellness movement, which can at times rely on junky science, but there’s solid research indicating they help us fight oxidative stress. Oxidative stress arises when our bodies turn food into fuel to produce the energy they need, but they can’t avoid also creating some free radicals in the process. Free radicals are simply oxygen atoms that have unpaired electrons. But as they zoom around your body looking for other single electrons to pair with they can do a lot of damage to your cells, which is why the term has become a buzzy one for scaring you into buying skincare products (sunscreen is still the business though, please wear it).

"It's preliminary, but you can see that countries that have more ergothioneine in their diets, countries like France and Italy, also have lower incidences of neurodegenerative diseases, while people in countries like the United States, which has low amounts of ergothioneine in the diet, have a higher probability of diseases like Parkinson's Disease and Alzheimer's," Beelman continued in the news release. Beelman emphasizes that the research has not determined whether the link is only correlation—a connection but not proven as a cause.

But the difference is striking, he notes: the average amount of the antioxidant seen in the diets in these countries is about 3 milligrams per day, or about five button mushrooms.